Azadirachtin inhibited a wider variety of soil and phytopathogenic bacteria than did the neem extract. This difference may be due to the small amount of azadirachtin in the neem leaf extract. It has been reported that while a small amount of azadirachtin is found in neem leaves, the compound is abundant in neem seed oil (Morgan, 2009). Alves et al. (2009) reported that azadirachtin could not be found in hydroalcoholic neem leaf extract via TLC or HPLCUV/DAD detection methods. This suggests that the antimicrobial activity of the neem extract is limited. Interestingly, the two-month long-term usage of the extract reduced the number of nodules found on the roots of mung beans, as well as the population of Trichoderma in the rhizosphere. This might be because neem extract application alters soil conditions, making them unsuitable for Rhizobium or Trichoderma colonization. Dubey et al. (2009) found that ammonia was evolved during the decomposition of neem oil and seed cakes. This ammonia production increased soil alkalinity, resulting in an increase in antimicrobial activity.